Begging for Parental Care from Another Species: Specialization and Generalization in Brood-Parasitic Finches

Abstract

African indigobirds (Vidua species) are species-specific brood parasites of estrildid finches. Although the mouth patterns of nestlings mimic their host nestlings, the begging calls of young indigobirds are not host-specific, and in only some species do they resemble begging calls of the host. Adult male indigobirds mimic calls and songs of their host species. Their song incorporates two kinds of begging call, an innate call like that used by nestling indigobirds, and a second learned one when males imprint and then mimic the foster species’ begging calls in male song. We recorded young and adult indigobirds in the field, and the begging calls of young and adult song mimics reared under alternative foster species. The innate begging calls in all indigobird species matched the begging calls of only certain firefinch(Lagonosticta) host species, even in indigobirds that normally parasitized other hosts. This innate call is used by nestlings to gain parental care. Both kinds of begging calls are used by adults in mate choice. Host-specific begging call in mimicry songs of adult male indigobirds would allow females to assess whether males were reared by their own foster species.